This disclosure relates to a manufacturing method for improving low cycle fatigue life of machined components, such as aircraft components.
Many machined components, such as disks and rotating shafts of gas turbine engines, are made from superalloys, such as nickel. Some nickel superalloys include brittle compound particles, such as carbides or oxides.
Typically, these superalloy components are machined subsequent to a casting or forging process. A cutting tool can damage or crack the carbides and/or oxides during machining, which provides weakened sites at which fatigue cracks may initiate. Fatigue cracks result in reduced low cycle fatigue life that can significantly limit the service life of the component. Superalloy components having carbides and/or oxides that have been low-stress ground exhibit improved low cycle fatigue life. Low-stress grinding is quite time consuming and expensive. Furthermore, low-stress grinding can only be utilized on smooth, readily accessible surfaces and cannot be used on inaccessible features, such as notches, which are typical on most aircraft superalloy components. Accordingly, fatigue cracks may initiate at inaccessible, machined surfaces of superalloy components despite the use of low-stress grinding.
What is needed is improved low cycle fatigue life for superalloy components with brittle compound particles and machined surfaces.